Indirect air heater



June 18, 1968 E. R. MUCKELRATH 3,388,697

INDIRECT AIR HEATER Filed Dec. 8, 1966 5 Sheets-Sheet l INVENTOR. Ernest l?. Mucke/rath,

N WWW 15% June 18,v 1968 Filed Deo.

Fig. 2

E. R. MUCKELRATH 3,388,697

INDIRECT AIR HEATER 5 Sheets-Sheet 2 June 18, 1968 E. R. MUCKELRATH 3,388,697

INDIRECT AIR HEATER- Filed Dec. 8, 1966 5 Sheets-Sheet 3 Ernest Macke/rath INVENTOR.

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United States Patent Oiiice 3,388,697 Patented June 18, 1958 3,388,697 HNDIRECT AIR HEATER Ernest R. Mnclrelrath, Tioga, N. Dak., assignor, by mesne assignments, of forty percent to Ernest R. Muekelrath,

thirty percent to Robert F. Ivowdy, .and thirty percent to W. S. Raymond Filed Dec. 8, 1966, Ser. No. 606,133 13 Ciams. (Cl. 126-110) ABSTRACT F THE DISCLOSURE An enlarged air heater for discharging large volumes of heated air toward outdoor work areas and the like comprising upper and lower tubular members within which bypassing non-communicating combustion and air passages are dened for progressively heating the air from the intake end to the discharge thereof. The combustion passage includes a re tube and an exhaust chamber while the air passage includes a preheating chamber generally coextensive with the exhaust chamber and a final heating chamber generally coextensive with the re tube.

The instant invention generally relates to heater assemblies, and is more particularly concerned with a warm air discharging heater particularly adapted to discharge large volumes of heated air toward exterior work areas, such as drilling sites, construction sites, or the like, so as to enable both men and machinery to perform work notwithstanding extremely cold weather conditions.

A significant object of the instant invention resides in the provision of an area heater which is capable of discharging a large volume of constant temperature heated air.

Another significant object of the-v instant invention resides in the provision of an air discharging heater wherein the discharged air is free of combustion products, thereby eliminating any potential danger which might arise, especially when working in or about oil drilling rigs.

In conjunction with the above object, another important object of the instant invention resides in the provision of an air heater wherein a heat exchange assembly is utilized with the heat supplying combustion products tubular passage being substantially coextensive with the air passage and out of air mixing communication therewith.

Further, it is an object of the instant invention to provide a heater assembly which provides for an initial or preheating of the introduced air prior to the final heating t thereof immediately before discharge.

In addition to achieving the above objects, it is considered an important object of the instant invention to provide an assembly which is of a compact, etiicient and durable nature capable of operation under extreme conditions as may be expected in the eld.

It is also an important object of the instant invention to provide a heater assembly which is constructed of sections capable of being easily bolted together into a continuous heat exchanging unit.

Basically, the area heater of the instant invention comprises an upper preheating section wherein the exhausting combustion products are introduced into an enlarged chamber through which a plurality of reduced diameter air intake tubes pass whereby a preheating of the introduced air is effected by the heat of the exhausting combustion products. The individual air intake tubes then discharge into a common air chamber from which the air moves downwardly through an enlarged heating chamber surrounding a generally concentric tire tube within which the heat source or burners are mounted. The heating chamber in turn communicates, at the far end thereof from that end at which the burner means is located, with a suitable blower on the like for a directing of the discharging air as desired. The path taken by the combustion products is completely segregated from that taken by the air, and as such, there is no commingling, notwithstanding the substantially coextensive paths.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

FIGURE 1 is a perspective view of the heater assembly comprising the instant invention;

FIGURE 2 is an enlarged cross-sectional view taken substantially on a plane passing along line 2-2 in FIG- URE 1;

FIGURE 3 is a cross-sectional view taken substantially on a plane passing along line 3--3 in FIGURE 2',

FIGURE 4 is an exploded perspective view of the various individual sections comprising the area heater of the instant invention; and

FIGURE 5 is an enlarged cross-sectional detail, taken substantially on a plane passing along line 5-5 in FIG- URE 2.

Referring now more specifically to the drawings, reference numeral 10 is used to generally designate the heater assembly or area heater comprising the instant invention. This assembly 10 consists basically of upper and lower tubular sections 12 and 14 mounted on a skid-like support 16.

The support 16 can consist of a pair of elongated ground-engaging side rails 18 interconnected by a plurality of crossbars 20 so as to define a rigid unit. The lower tubular section 14 can be supported on the support base 16 by means of a series of web-like cradles 22 extending transversely across the support 16 between pairs of restraining uprights 24 rigidly aixed, as by welding, to the rails 18. The upper section 12 is to be supported in spaced relation above the lower section 14 utilizing similar web-like cradles 25 also engaged between selected ones of the rigid uprights 24, in addition to mated interconnected duct sections on the upper and lower tubular sections 12 and 14 as shall be described in more detail subsequently.

The lower section 14 includes an outer enlarged and elongated cylindrical tube 26 which denes the main heating chamber 28. This heating chamber 28 communicates directly with a longitudinally aligned converging discharge i operatively engaged with the intake end 32 of any suitable blower apparatus 34 by means of which the flow of air through the area heater 10 and therefrom is controlled. This blower assembly 34 will of course also be supported on the skid-type support 16, as for example on an enlarged platform 36 provided just forward of the heating chamber discharge 30.

The lower section 14 also includes an elongated cylindrically shaped tubular -tire tube 38 extending substantially concentrically through the heating chamber 28 and slightly beyond the end thereof opposite from the discharge 30, this end being completely sealed about the tire tube 38 by an annular end plate 40. The outer end of the re tube 38 is selectively closed by a pivotally mounted access plate 42 having a central air intake and observation hole 44 therein. A second, and substantially enlarged, air intake opening 46 is provided through the lower portion of the re tube 38 outward of the closure plate 40 of the heating chamber 28 immediately forward of the access plate 42 with the burner assembly 48 being mounted within the fire tube 38 just inward of the opening 46, thus in effect locating the burner assembly 48 at the closed end of the heating chamber tube 26. As will be best appreciated from FIGURE 2. The burner assembly 48 can be of any appropriate type attached, through a suitable supply conduit 50, to an appropriate fuel supply which may be natural gas, liquid petroleum gas, diesel fuel oil, ctc. Further, it should of course be appreciated that the burner assembly 48 can consist of one or more burner heads.

The forward end of the fire tube 38, sealed by a closure plate 52, is located just inward of the nozzle-like discharge section 30 of the heating chamber 28. A vertically extending duct section 54 is sealed to the upper portieri of the fire tube 38 adjacent the closed inner end thereof and projects therefrom through the upper portion of the heating chamber tube 26 to which it is also peripherally sealed in an airtight manner. Projecting above the top of the heating chamber tube 26, the duct section S4 terminates in a laterally outward directed peripheral mounting flange 56 for the reception thereon of a mating portion of the upper section 12. Thus, it will be appreciated that the fire tube 38 is supported at the opposite ends thereof. lf additional support should be needed, this can be provided by hanger bars 58 welded to the re tube 38 and the overhead interior surface of the heating chamber tube 26, either with or without a lower brace 60 projecting upwardly from the bottom of the heating chamber 28 and engaging the bottom of the fire tube 38. It will be appreciated that such braces 58 and 60 will in no way interfere with the free flow of air through the heating chamber 28 in the desired manner.

The lower section 14 is completed by a vertically extending duct section 62 peripherally sealed to the top of the heating chamber tube 26 adjacent the closure plate 40 and in flow permitting communication therewith. This duct section 62 also terminates in an upwardy spaced lateral outwardly directed peripheral mounting flange 64 for the reception of a mating portion of the upper section 12. Incidently, in order that the duct section 54 not block the free flow of air toward the discharge 30, it will be noted that a tubular air passage 66 has been provided centrally therethrough, thereby avoiding any dead air space.

The upper or preheating section 12 includes an elongated cylindrical tube 68 divided into an elongated exhaust chamber 70 and a relatively smaller air chamber 72 by means of a transversely positioned bulkhead-like plate 74 peripherally sealed about the inner surface of the tube 68. The plate 74 is provided just forward of a depending duct section 76 which aligns with the lower tube duct section 62, with the air chamber 72 being defined between the plate 74 and a closure plate or panel 78 sealing the rear end of the tube 68. The depending duct section 76, as will be appreciated from the drawings, is also provided with a lateral outwardly directed flange S peripherally about the lower end thereof, this flange 80 seating on and being bolted directly to the flange 64 on the upwardly projecting lower duct section 62, thereby providing for a sealed air passave between the upper air chamber 72 and the lower heating chamber 28 through the constant diameter duct sections 62 and 76.

The exhaust chamber 70 extends along the major portion of the upper tube 68 from the bulkhead forming plate 74 to the opposite or forward end of the tube 63 sealed by a circular plate 82. This exhaust chamber 70 is communicated with the tire tube 38 in the lower tube Z6 through a depending duct section 84 which includes a peripheral mounting flange 86 about the lower edge thereof for seating yand bolted engagement with the peripheral flange 56 on the upwardly projecting duct section S4 which communicates directly with the interior of the forward end of the lire tube 38. A vertically projecting exhausting duct section 88 extends upwardly from communication with the exhaust chamber 70 adjacent the inner dividing plate 74, the duct section 88 terminating in a lateral outwardly directed mounting flange 90 which receives a similar flange 92 provided peripherally about 4.- the lower end of a vertically elongated flue stack 94. The flanges 99 and 92 are of course suitably bolted together.

Fresh air is introduced into the heater assembly 10 through a plurality of reduced diameter air intake tubes 96 which extend longitudinally through the exhaust chamber '70 and through the plates 74 and 82 at the opposite ends thereof. These air intake tubes 96 are peripherally sealed to the plates 74 and 82 and are completely segregated from the exhaust chamber whereby no mingling of the fresh air with the combustion products is possible. A screen 98 will normally be provided over the outer or intake ends Miti of the air intake tube 96 so as to prevent the entry of undesirable foreign matter thereinto.

In order to afford access to the interior of the upper section 12 of the assembly, a laterally opening manhole 162 is provided centrally through the rear closure plate 78, this manhole being selectively closed by a removable cover G4 bolted to a peripheral flange 166 defined thereabout. Access to the exhaust chamber 70 is provided for by pivotally mounting an enlarged door forming portion 108 along the top of the tube 68 as will be best appreciated from FIGURES 1 and 4. This door forming portion 168 can be mounted in any suitable manner, such as by hinge means 110, and can also include a suitable handle 112 and latch means for locking the portion closed. As noted in the drawings, inasmuch as the door forming portion w8 extends along substantially the entire length of the exhaust chamber 7i), the flue mounting duct section 88 is mounted directly thereon.

From the foregoing, it will be appreciated that the assembled area heater 10 comprising the instant invention includes a pair of elongated substantially coextensive ow passages, one constituting a passage for the combustion products, and the other constituting a ow passage for the air to be heated by the heat exchanger relationship between the passages. In operation, upon an activation of the blower 34, fresh air is drawn into the air intake tubes 96 from the screen protected forward end of the upper tube 68. Because of the substantial surface area provided by the use of a plurality of relatively small air intake tubes 96, an effective heating of the air by the exhaust products from the tire tube 3S being discharged into the exhaust chamber 70 will result. The preheated air, subsequent to movement through the air intake preheating tubes 96, is discharged into the enlarged air chamber 72 from whence it moves downwardly through the communicating duct sections 76 and 62 and into the enlarged heating chamber 28. In the heating chamber 28, the air moves forwardly, completely about the hot burner supplied fire tube 38, for ultimate discharge through the discharge structure 30 just forward of the forward end of the re tube 38. The preheating of relatively narrow individual streams of fresh air prior to an introduction of the air into the main heating chamber 28 itself insures an even and constant temperature flow of air from the unit 10 with there being no passing of cold air directly over the extremely high temperature fire tube 38. As noted supra, in order to avoid a dead air space in the vicinity of the vertical fire tube duct section 54, a separate air passage 66 is provided completely therethrough.

With regard to the combustion products passage, it will be noted that the burner assembly 48 is located substantially directly below the discharging duct of the air chamber 72 with the combustion being forwardly directed along the length of the fire tube 38 so as to provide the maximum heat for transfer to the fresh air ow immediately prior to a dischargeL of this air flow through the blower 34. The burner assembly 48 is supplied with air through the air intake openings 44 and 46 immediately to the rear thereof with the combustion products exhausting into the exhaust chamber 70 through the vertical duct sections 54 and 84 at the forward end of the lire tube 38. The exhaust products, in the exhaust chamber, are efficiently utilized so as to effect a preheatin'g of the air owing through the air intake tubes 96 prior to a discharge of the combustion products through the flue stack 94. In this manner, it will be appreciated that an effective use of all of the heat generated by the burner assemblies 48 results. Further, a maximum efficient utilization of the burner produced heat is effected in that the heated air, along the last leg of its movement through the heater 10, moves longitudinally along the fire tube 3S, completely thereabout, and discharges longitudinally along the same path of movement without any heat dissipating bends or turns.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention as claimed.

What is claimed as new is as follows:

1. An air heater assembly comprising elongated combustion passage means, and substantially coextensive air passage means, each of said passage means comprising an inlet end and an outlet end, burner means mounted at the inlet end of said combustion passage means, fine means mounted at the outlet end of said combustion passage means, air intake means defined at the inlet end of said air passage means, and air discharge means defined at the outlet end of said air passage means, said combustion passage means including a fire tube extending inwardly from the inlet end thereof, and an exhaust chamber communicated with and between the inner end of the fire tube and flue means, said air passage means including a preheating portion in heat exchange relation to said exhaust chamber, and a final heating chamber communicated with and between the preheating portion and the air discharge means, said final heating chamber being in heat exchange relation to said fire tube, said preheating portion of the air passage means comprising a plurality of elongated air intake tubes extending longitudinally through said exhaust chamber independent of each other, thereby defining a substantial surface area for heat exchange purposes, said final heating chamber comprising an elongated chamber defined coaxially about said fire tube and having an internal diameter substantially greater than that of said fire tube, said fire tube and said final heating chamber thereabout both extending longitudinally throughout the length thereof, said air discharge means being positioned coaxially with said final heating chamber longitudinally beyond the inner end of said fire tube for the straight discharge of heated air therefrom, and a common air chamber inward of the inner ends of said air intake tubes for a mingling of the air from said air intake tubes, said air chamber cornmunicating directly with said final heating chamber for the introduction of the air thereinto, said final heating chamber and said fire tube both having a constant crosssection throughout the length thereof, said exhaust chamber and said air chamber being defined Within a single elongated internally partitioned tubular member, said final heating chamber being defined by a second tubular member parallel to said first tubular member and laterally aligned therewith, first separable duct means communicating the inner end of said fire tube with said exhaust chamber and second separable duct means communicating said air chamber with said final heating chamber.

2. The assembly of claim l wherein said burner means is mounted within the inlet end portion of the fire tube, and an air intake opening communicating said fire tube directly with the atmosphere adjacent the burner means.

3. The assembly of claim 1 wherein said tubular members are horizontally positioned in vertically spaced relation to each other, and ground-engaging support means for said tubular members, said support means compris- 5 ing a base portion, a plurality of pairs of uprights affixed to said base portion with the uprights of each pair being located to the opposite sides of said tubular members, and support cradles rigid with the uprights of each pair and underlying the tubular members in supporting engagement therewith.

4. An air heater assembly comprising upper and lower generally coextensive elongated tubes, a transverse panel in said upper tube defining an elongated exhaust chamber and a relatively shorter air chamber, a plurality of air tubes extending independently through said exhaust chamber and into communication with said air chamber, said air tubes defining internal air passages out of communication with said exhaust chamber, the ends of said air tubes opposite from said air chamber being open for the intake of air therethrough, said lower tube defining an enlarged internal chamber, an elongated fire tube mounted longitudinally within said lower tube chamber, duct means communicating said air chamber with said lower tube chamber, duct means communicating said fire tube with said exhaust chamber adjacent the open ends of said exhaust chamber received air tubes, a burner assembly in said fire tube adjacent said first mentioned duct means, and a discharge opening in said lower tube chamber adjacent said second mentioned duct means.

5. The air heater assembly of claim 4 wherein each of said duct means comprises a pair of duct sections and means releasably interlocking said duct sections.

6. The air heater assembly of claim 5 wherein said second mentioned duct means, within said lower tube chamber, includes a transverse air passage defined therethrough generally parallelling the longitudinal axis of the lower tube.

7. The air heater assembly of claim 6 including a ground-engaging support for said upper and lower tubes, said support comprising a plurality of longitudinally spaced cradle portions and laterally opposed vertically extending support uprights.

8. The air heater assembly of claim '7 including air intake openings communicating said fire tube directly with the atmosphere adjacent the burner assembly, and access panels provided for selectively exposing the interior of said exhaust chamber and said air chamber.

9. The air heater assembly of claim 4 including a ground-engaging support for said upper and lower tubes, said support comprising a base portion, longitudinally spaced pairs of uprights rigid with said base portion, the uprights of each pair being orientated to opposite sides of said tubes, and support cradles afiixed to the uprights of each pair and underlying the upper and lower tubes in supporting relation thereto.

it?. An air heater assembly comprising elongated combustion passage means, and substantially coextensive air passage means, each of said passage means comprising an inlet end and an outlet end, burner means at the inlet end of said combustion passage means, flue means mounted at the outlet end of said combustion passage means, air intake means defined at the inlet end of said air passage means, and air discharge means defined at the outlet end of said air passage means, said combustion passage means including a fire tube extending inwardly from the inlet end thereof, and an exhaust chamber communicated with and between the inner end of the fire tube and fiue means, said air passage means including a preheating portion in heat exchange relation to said exhaust chamber, and a final heating chamber communicated with and between the preheating portion and the air discharge means, said final heating chamber being in heat exchange relation to said fire tube, said preheating portion of the air passage means comprising air intake tube means extending longitudinally through said exhaust chamber and out of fiow passing communication therewith, said final heating chamber comprising an elongated chamber defined about said fire tube and havr ing an internal diameter substantially lgreater than that of said fire tube, said fire tube and said final heating chamber thereabout both extending longitudinally throughout the length thereof, said air discharge means being positioned longitudinally beyond the inner end of said re tube for the straight discharge of the heated air therefrom, and an air chamber inward of the inner end of the air intake tube means for reception of the preheated air therefrom, said air chamber communicating directly with said nal heating chamber for the introduction of the air thereinto, said inal heating chamber and said tire tube both having a generally constant crosssection throughout the length thereof, said exhaust chamber and said air chamber being defined Within a single elongated internally partitioned tubular member, said nal heating chamber being defined by a second tubular member parallel to said rst tubular member and laterally aligned therewith.

11. The assembly of claim 10 including first separable duct means communicating the inner end of said re tube with said exhaust chamber, and second separable yduct means communicating said air chamber with said final heating chamber.

12. An air heater assembly comprising upper and lower generally coextensive elongated tubes, a transverse panel in said upper tube deining an elongated exhaust chamber and an air chamber at one end thereof, a plurality of air tubes extending independently through said exhaust chamber and into communication with said air chamber, said air tubes defining internal air passages out of communication with said exhaust chamber, the ends of said air tubes opposite from said air chamber being open for the intake of air therethrough, said lower tube dening an enlarged internal chamber, an elongated fire tube mounted longitudinally within said lower tube chamber, means communicating said air chamber with said lower tube chamber, means communicating said tire tube with said exhaust chamber adjacent the open ends of said exhaust chamber received air tubes, burner means operatively associated with said tire tube adjacent said means communicating said air chamber with said lower tube chamber, and a discharge opening in said lower tube chamber adjacent said means communicating said iire tube with said exhaust chamber.

13. The air heater assembly of claim 12 wherein said means communicating said air chamber with said lower tube chamber and said means communicating said re tube with said exhaust chamber comprise a pair of ducts, each duct in turn comprising a pair of duct sections, and means releasably interlocking the duct sections of each duct References Cited UNITED STATES PATENTS 1,619,567 3/1927 Croan 126-104 2,089,407 8/ 1937 Norris 126-117 X 2,699,769 1/1955 Arndt 126-110 3,106,200 10/1963 Muckelrath 126-109 JAMES W. WESTHAVER, Primary Examiner. 

